The goal of the proposed study is to answer the question: "For which subgroups of Hispanic adolescents are specific drug use and HIV preventive interventions efficacious and for whom are they not?" This application proposes to answer this question by conducting secondary data analysis with this highly vulnerable population. The proposed study will be accomplished through two aims. AIM 1 is to identify classes of risk for this population. Classes of risk will be identified at baseline based on individual level variables (i.e., attitudes, beliefs, and intentions regarding drug use and sexual behavior) and ecodevelopmental variables (i.e., family functioning, parental monitoring of adolescent's peers, and the adolescent's orientation toward the American culture). AIM 1 will be tested by hierarchical cluster analyses and discrete latent mixtures. AIM 2 is to estimate the efficacy of the preventive interventions with respect to preventing drug use and unsafe sexual behavior across the classes of risk identified in Aim 1. Hierarchical Linear Modeling will be used to test AIM 2. Planned post-hoc analyses will be conducted to (a) explore the efficacy of the interventions within the classes identified and (b) the mechanisms that may mediate the effects of the intervention within each of the classes. Findings that intervention efficacy varies as a function of individual's class membership and that intervention efficacy is mediated by different variables within class will have implications for the development of a new generation of drug use and HIV preventive interventions for Hispanic adolescents. Specifically, the results of this study will help determine what specific ecodevelopmental and individual factors need to be targeted within different subgroups of Hispanic adolescents to maximize intervention efficacy/effectiveness in preventing drug use and HIV. This study has the potential to help reduce health disparities in Hispanic populations.